Applying multiple processes nonequilibrium model to investigate cesium transport in crushed granite

Abstract Understanding the movement of radionuclides (RN) in the subsurface environment is of paramount importance, particularly when it comes to the planning and assessment of facilities devoted to the disposal of radioactive waste. Comprehensive mathematical models serve as indispensable tools in this regard, demanding a profound and thorough understanding of the intricate mechanisms underlying radionuclide transport. The effective application of these models is contingent upon accurately determining the required input parameters. This is a critical aspect to consider given the inherent physical and chemical variations exhibited by the subsurface environment. These variations can induce significant effects on the movement of RNs below ground, potentially altering the predicted outcomes of radionuclide transport. This paper presents the findings of a comprehensive investigation that was conducted utilizing both advective-dispersive experiments (ADE) and multiple processes nonequilibrium (MPNE) inversion. These methodologies were employed using the advanced HYDRUS code, which is highly regarded in the field. The research specifically focuses on the transportation mechanisms of Cesium (Cs), a common radionuclide, in a medium of crushed granite. The study considers varying conditions, including different flow rates and column lengths, to provide a broad understanding of the behavior of Cs. The findings reveal that the transport behavior of Cs is not only influenced by the different flow rates and column lengths but is also significantly affected by the diffusive mass transfer and nonequilibrium sorption. These factors collectively contribute to our understanding of the complex processes involved in radionuclide transport.